System and method for securing engine torque requests

ABSTRACT

A control system for an engine includes an engine torque request module, an engine torque response module, a torque command limit module, and an actuation module. The engine torque request module determines an engine torque request based on (i) an engine power request and (ii) a desired engine speed (DRPM). The engine torque response module determines first and second torque values based on (i) an engine torque response model and (ii) first and second torque boundaries, wherein the first and second torque boundaries are based on the DRPM and a measured engine speed (RPM). The torque command limit module generates a secured engine torque request based on (i) the engine torque request and (ii) the first and second torque values. The actuation module controls at least one actuator of the engine based on the secured engine torque request.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to commonly-assigned U.S. patent applicationSer. No. 12/621,823, filed on Nov. 19, 2009 (U.S. Pub. No. 2011-0118955Al), and commonly-assigned U.S. patent application Ser. No. 13/166,232,filed on Jun. 22, 2011. The disclosures of the above applications areincorporated herein by reference in their entirety.

FIELD

The present disclosure relates to internal combustion engines and moreparticularly to a system and a method for securing engine torquerequests.

BACKGROUND

The background description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description that may nototherwise qualify as prior art at the time of filing, are neitherexpressly nor impliedly admitted as prior art against the presentdisclosure.

Internal combustion engines combust an air and fuel mixture withincylinders to drive pistons, which produces drive torque. Air flow intothe engine is regulated via a throttle. More specifically, the throttleadjusts throttle area, which increases or decreases air flow into theengine. As the throttle area increases, the air flow into the engineincreases. A fuel control system adjusts the rate that fuel is injectedto provide a desired air/fuel mixture to the cylinders and/or to achievea desired torque output. Increasing the amount of air and fuel providedto the cylinders increases the torque output of the engine.

In spark-ignition engines, spark initiates combustion of an air/fuelmixture provided to the cylinders. In compression-ignition engines,compression in the cylinders combusts the air/fuel mixture provided tothe cylinders, Spark timing and air flow may be the primary mechanismsfor adjusting the torque output of spark-ignition engines, while fuelflow may be the primary mechanism for adjusting the torque output ofcompression-ignition engines.

Engine control systems have been developed to control engine outputtorque to achieve a desired torque. Traditional engine control systems,however, do not control the engine output torque as accurately asdesired. Further, traditional engine control systems do not provide arapid response to control signals or coordinate engine torque controlamong various devices that affect the engine output torque.

SUMMARY

A control system for an engine includes an engine torque request module,an engine torque response module, a torque command limit module, and anactuation module. The engine torque request module determines an enginetorque request based on (i) an engine power request and (ii) a desiredengine speed (DRPM). The engine torque response module determines firstand second torque values based on (i) an engine torque response modeland (ii) first and second torque boundaries, wherein the first andsecond torque boundaries are based on the DRPM and a measured enginespeed (RPM). The torque command limit module generates a secured enginetorque request based on (i) the engine torque request and (ii) the firstand second torque values. The actuation module controls at least oneactuator of the engine based on the secured engine torque request.

A method for controlling an engine includes determining an engine torquerequest based on (i) an engine power request and (ii) a desired enginespeed (DRPM), determining first and second torque values based on (i) anengine torque response model and (ii) first and second torqueboundaries, wherein the first and second torque boundaries are based onthe DRPM and a measured engine speed (RPM), generating a secured enginetorque request based on (i) the engine torque request and (ii) the firstand second torque values, and controlling at least one actuator of theengine based on the secured engine torque request.

Further areas of applicability of the present disclosure will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples areintended for purposes of illustration only and are not intended to limitthe scope of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a functional block diagram of an example engine system;

FIG. 2 is a functional block diagram of an example engine control module(ECM);

FIG. 3 is a functional block diagram of an example driver torque module;and

FIG. 4 is a flow diagram illustrating an example method for securingengine torque requests.

DETAILED DESCRIPTION

The following description is merely illustrative in nature and is in noway intended to limit the disclosure, its application, or uses. Forpurposes of clarity, the same reference numbers will be used in thedrawings to identify similar elements. As used herein, the phrase atleast one of A, B, and C should be construed to mean a logical (A or Bor C), using a non-exclusive logical or. It should be understood thatsteps within a method may be executed in different order withoutaltering the principles of the present disclosure.

As used herein, the term module may refer to, be part of, or include anApplication Specific Integrated Circuit (ASIC); an electronic circuit; acombinational logic circuit; a field programmable gate array (FPGA); aprocessor (shared, dedicated, or group) that executes code; othersuitable hardware components that provide the described functionality;or a combination of some or all of the above, such as in asystem-on-chip. The term module may include memory (shared, dedicated,or group) that stores code executed by the processor.

The term code, as used above, may include software, firmware, and/ormicrocode, and may refer to programs, routines, functions, classes,and/or objects. The term shared, as used above, means that some or allcode from multiple modules may be executed using a single (shared)processor. In addition, some or all code from multiple modules may bestored by a single (shared) memory. The term group, as used above, meansthat some or all code from a single module may be executed using a groupof processors or a group of execution engines. For example, multiplecores and/or multiple threads of a processor may be considered to beexecution engines. In various implementations, execution engines may begrouped across a processor, across multiple processors, and acrossprocessors in multiple locations, such as multiple servers in a parallelprocessing arrangement. In addition, some or all code from a singlemodule may be stored using a group of memories.

The apparatuses and methods described herein may be implemented by oneor more computer programs executed by one or more processors. Thecomputer programs include processor-executable instructions that arestored on a non-transitory tangible computer readable medium. Thecomputer programs may also include stored data. Non-limiting examples ofthe non-transitory tangible computer readable medium are nonvolatilememory, magnetic storage, and optical storage.

As previously described, an engine control system may control an engineto achieve a desired torque. Specifically, the engine control system maycontrol the engine based on an engine torque request. The engine torquerequest may be based on input from a driver of a vehicle, vehicle speed,and/or other operating parameters. The engine torque request may bebased further on desired engine speed. Engine speed refers to arotational speed of a crankshaft of the engine and may be measured inrevolutions per minute (RPM). Therefore, the desired engine speed mayalso be referred to as desired RPM, or DRPM.

Controlling engine torque based on engine speed feedback, however, maycause disturbances in vehicle drivability. More specifically, the enginespeed may change rapidly and therefore the engine speed feedback mayhave oscillations that propagate through the engine control system. Theengine speed fluctuations may cause the engine control system togenerate an engine torque request outside of a desired range. Thisengine speed based engine torque request, therefore, may also bereferred to as an unsecured engine torque request. In other words, theengine torque request is not prevented from deviating from the desiredrange. Engine torque requests outside of the desired range may causedisturbances which decrease vehicle drivability.

Accordingly, a system and method are presented for securing enginetorque requests. More specifically, the system and method are directedto generating a secured engine torque request for controlling an engine,thereby improving vehicle drivability and/or decreasing calibrationcosts. The system and method may first determine an engine torquerequest based on (i) an engine power request and (ii) DRPM. The systemand method may determine the DRPM based on the engine power request,turbine speed, and/or torque converter clutch (TCC) slip. The system andmethod may implement a feed-forward controller to determine the enginetorque request based on (i) the engine power request and (ii) the DRPM.The system and method may determine the engine power request based on(i) driver input and (ii) vehicle speed.

The system and method may determine a secured torque based on (i) theDRPM and (ii) a measured RPM. The system and method may determine firstand second torque boundaries based on (i) the secured torque, (ii)driver input, and (iii) vehicle speed. The system and method maydetermine first and second torque values based on (i) an engine torqueresponse model and (ii) the first and second torque boundaries. Theengine torque response model may include at least one of (i) a timedelay and (ii) a rate limit. The system and method may generate thesecured engine torque request based on (i) the engine torque request and(ii) the first and second torque values. More specifically, the systemand method may limit the engine torque request to a value between thefirst and second torque values. The system and method may then controlthe engine based on the secured engine torque request.

Referring now to FIG. 1, a functional block diagram of an example enginesystem 100 is presented. The engine system 100 includes an engine 102that combusts an air/fuel mixture to produce drive torque for a vehiclebased on driver input from a driver input module 104. Air is drawn intoan intake manifold 110 through a throttle valve 112. For example only,the throttle valve 112 may include a butterfly valve having a rotatableblade. An engine control module (ECM) 114 controls a throttle actuatormodule 116, which regulates opening of the throttle valve 112 to controlthe amount of air drawn into the intake manifold 110.

Air from the intake manifold 110 is drawn into cylinders of the engine102. While the engine 102 may include multiple cylinders, forillustration purposes a single representative cylinder 118 is shown. Forexample only, the engine 102 may include 2, 3, 4, 5, 6, 8, 10, and/or 12cylinders. The ECM 114 may instruct a cylinder actuator module 120 toselectively deactivate some of the cylinders, which may improve fueleconomy under certain engine operating conditions.

The engine 102 may operate using a four-stroke cycle. The four strokes,described below, are named the intake stroke, the compression stroke,the combustion stroke, and the exhaust stroke. During each revolution ofa crankshaft (not shown), two of the four strokes occur within thecylinder 118. Therefore, two crankshaft revolutions are necessary forthe cylinder 118 to experience all four of the strokes.

During the intake stroke, air from the intake manifold 110 is drawn intothe cylinder 118 through an intake valve 122. The ECM 114 controls afuel actuator module 124, which regulates fuel injection to achieve adesired air/fuel ratio. Fuel may be injected into the intake manifold110 at a central location or at multiple locations, such as near theintake valve 122 of each of the cylinders. In various implementations(not shown), fuel may be injected directly into the cylinders or intomixing chambers associated with the cylinders. The fuel actuator module124 may halt injection of fuel to cylinders that are deactivated.

The injected fuel mixes with air and creates an air/fuel mixture in thecylinder 118. During the compression stroke, a piston (not shown) withinthe cylinder 118 compresses the air/fuel mixture. The engine 102 may bea compression-ignition engine, in which case compression in the cylinder118 ignites the air/fuel mixture. Alternatively, the engine 102 may be aspark-ignition engine, in which case a spark actuator module 126energizes a spark plug 128 in the cylinder 118 based on a signal fromthe ECM 114, which ignites the air/fuel mixture. The timing of the sparkmay be specified relative to the time when the piston is at its topmostposition, referred to as top dead center (TDC).

The spark actuator module 126 may be controlled by a timing signalspecifying how far before or after TDC to generate the spark. Becausepiston position is directly related to crankshaft rotation, operation ofthe spark actuator module 126 may be synchronized with crankshaft angle.In various implementations, the spark actuator module 126 may haltprovision of spark to deactivated cylinders.

Generating the spark may be referred to as a firing event. The sparkactuator module 126 may have the ability to vary the timing of the sparkfor each firing event. The spark actuator module 126 may even be capableof varying the spark timing for a next firing event when the sparktiming is changed between a last firing event and the next firing event.

During the combustion stroke, the combustion of the air/fuel mixturedrives the piston down, thereby driving the crankshaft. The combustionstroke may be defined as the time between the piston reaching TDC andthe time at which the piston returns to bottom dead center (BDC).

During the exhaust stroke, the piston begins moving up from BDC andexpels the byproducts of combustion through an exhaust valve 130. Thebyproducts of combustion are exhausted from the vehicle via an exhaustsystem 134.

The intake valve 122 may be controlled by an intake camshaft 140, whilethe exhaust valve 130 may be controlled by an exhaust camshaft 142. Invarious implementations, multiple intake camshafts (including the intakecamshaft 140) may control multiple intake valves (including the intakevalve 122) for the cylinder 118 and/or may control the intake valves(including the intake valve 122) of multiple banks of cylinders(including the cylinder 118). Similarly, multiple exhaust camshafts(including the exhaust camshaft 142) may control multiple exhaust valvesfor the cylinder 118 and/or may control exhaust valves (including theexhaust valve 130) for multiple banks of cylinders (including thecylinder 118).

The cylinder actuator module 120 may deactivate the cylinder 118 bydisabling opening of the intake valve 122 and/or the exhaust valve 130.In various other implementations, the intake valve 122 and/or theexhaust valve 130 may be controlled by devices other than camshafts,such as electromagnetic actuators.

The time at which the intake valve 122 is opened may be varied withrespect to piston TDC by an intake cam phaser 148. The time at which theexhaust valve 130 is opened may be varied with respect to piston TDC byan exhaust cam phaser 150. A phaser actuator module 158 may control theintake cam phaser 148 and the exhaust cam phaser 150 based on signalsfrom the ECM 114. When implemented, variable valve lift (not shown) mayalso be controlled by the phaser actuator module 158.

The engine system 100 may include a boost device that providespressurized air to the intake manifold 110. For example, FIG. 1 shows aturbocharger including a hot turbine 160-1 that is powered by hotexhaust gases flowing through the exhaust system 134. The turbochargeralso includes a cold air compressor 160-2, driven by the turbine 160-1,that compresses air leading into the throttle valve 112. In variousimplementations, a supercharger (not shown), driven by the crankshaft,may compress air from the throttle valve 112 and deliver the compressedair to the intake manifold 110.

A wastegate 162 may allow exhaust to bypass the turbine 160-1, therebyreducing the boost (the amount of intake air compression) of theturbocharger. The ECM 114 may control the turbocharger via a boostactuator module 165. The boost actuator module 165 may modulate theboost of the turbocharger by controlling the position of the wastegate162. In various implementations, multiple turbochargers may becontrolled by the boost actuator module 165. The turbocharger may havevariable geometry, which may be controlled by the boost actuator module165.

An intercooler (not shown) may dissipate some of the heat contained inthe compressed air charge, which is generated as the air is compressed.The compressed air charge may also have absorbed heat from components ofthe exhaust system 134. Although shown separated for purposes ofillustration, the turbine 160-1 and the compressor 160-2 may be attachedto each other, placing intake air in close proximity to hot exhaust.

The engine system 100 may include an exhaust gas recirculation (EGR)valve 164, which selectively redirects exhaust gas back to the intakemanifold 110. The EGR valve 164 may be located upstream of theturbocharger's turbine 160-1. An EGR actuator module 166 may control theEGR valve 164 based on signals from the ECM 114.

The engine system 100 may measure the speed of the crankshaft inrevolutions per minute (RPM) using an RPM sensor 170. The temperature ofthe engine coolant may be measured using an engine coolant temperature(ECT) sensor 171. The ECT sensor 171 may be located within the engine102 or at other locations where the coolant is circulated, such as aradiator (not shown).

The pressure within the intake manifold 110 may be measured using amanifold absolute pressure (MAP) sensor 172. In various implementations,engine vacuum, which is the difference between ambient air pressure andthe pressure within the intake manifold 110, may be measured. The massflow rate of air flowing into the intake manifold 110 may be measuredusing a mass air flow (MAF) sensor 173. In various implementations, theMAF sensor 173 may be located in a housing that also includes thethrottle valve 112.

The throttle actuator module 116 may monitor the position of thethrottle valve 112 using one or more throttle position sensors (TPS)174. For example, first and second throttle position sensors 174-1 and174-2 monitor the position of the throttle valve 112 and generate firstand second throttle positions (TPS1 and TPS2), respectively, based onthe throttle position. The ambient temperature of air being drawn intothe engine 102 may be measured using an intake air temperature (IAT)sensor 175. The ECM 114 may use signals from the sensors and/or one ormore other sensors to make control decisions for the engine system 100.

The engine 102 outputs torque to a torque converter 176 via a flywheel177, such as a dual mass flywheel (DMF). The torque converter 176includes a torque converter clutch 178, a turbine (not shown), and animpeller (not shown). The turbine drives rotation of a transmissioninput shaft (not shown). Rotational speed of the turbine (turbine speed)may be measured using a turbine speed sensor 179. For example only, theturbine speed may be measured based on the rotational speed of thetransmission input shaft or another suitable parameter indicative of therotational speed of the turbine of the torque converter 176. Based on agear ratio selected within a transmission 180, torque is transferredbetween the transmission input shaft and a transmission output shaft(not shown). Torque may be transferred to wheels of the vehicle via thetransmission output shaft.

A transmission control module 194 may control operation of thetransmission 180 and the TCC 178. The ECM 114 may communicate with thetransmission control module 194 for various reasons, such as to shareparameters, and to coordinate engine operation with shifting gears inthe transmission 180 and/or operation of the TCC 178. For example, theECM 114 may selectively reduce engine torque during a gear shift. TheECM 114 may communicate with a hybrid control module 196 to coordinateoperation of the engine 102 and an electric motor 198.

The electric motor 198 may also function as a generator, and may be usedto produce electrical energy for use by vehicle electrical systemsand/or for storage in a battery. In various implementations, variousfunctions of the ECM 114, the transmission control module 194, and thehybrid control module 196 may be integrated into one or more modules.

Each system that varies an engine parameter may be referred to as anactuator that receives an actuator value. For example, the throttleactuator module 116 may be referred to as an actuator and the throttleopening area may be referred to as the actuator value. In the example ofFIG. 1, the throttle actuator module 116 achieves the throttle openingarea by adjusting an angle of the blade of the throttle valve 112.

Similarly, the spark actuator module 126 may be referred to as anactuator, while the corresponding actuator value may be the amount ofspark advance relative to cylinder TDC. Other actuators may include thecylinder actuator module 120, the fuel actuator module 124, the phaseractuator module 158, the boost actuator module 165, and the EGR actuatormodule 166. For these actuators, the actuator values may correspond tonumber of activated cylinders, fueling rate, intake and exhaust camphaser angles, boost pressure, and EGR valve opening area, respectively.The ECM 114 may control actuator values in order to cause the engine 102to generate a desired engine output torque.

Referring now to FIG. 2, a functional block diagram of an example enginecontrol system is presented. An example implementation of the ECM 114includes a driver torque module 202, an axle torque arbitration module204, and a propulsion torque arbitration module 206. The ECM 114 mayinclude a hybrid optimization module 208. The example implementation ofthe ECM 114 also includes a reserves/loads module 220, an actuationmodule 224, an air control module 228, a spark control module 232, acylinder control module 236, and a fuel control module 240. The exampleimplementation of the ECM 114 also includes a boost scheduling module248 and a phaser scheduling module 252.

The driver torque module 202 (see also FIG. 3 and the correspondingdescription below) may determine a secured engine torque request 253based on a driver input 254 from the driver input module 104. The driverinput 254 may be based on, for example, a position of an acceleratorpedal and a position of a brake pedal. The driver input 254 may also bebased on cruise control, which may be an adaptive cruise control systemthat varies vehicle speed to maintain a predetermined followingdistance. The driver torque module 202 may determine the secured enginetorque request 253 further based on a vehicle speed 255. For exampleonly, the vehicle speed 255 may be generated based on one or moremeasured wheel speeds, a transmission output shaft speed, and/or one ormore other suitable parameters.

An axle torque arbitration module 204 arbitrates between the securedengine torque request 253 and other axle torque requests 256. Axletorque (torque at the wheels) may be produced by various sourcesincluding an engine and/or an electric motor. Generally, torque requestsmay include absolute torque requests as well as relative torque requestsand ramp requests. For example only, ramp requests may include a requestto ramp torque down to a minimum engine off torque or to ramp torque upfrom the minimum engine off torque. Relative torque requests may includetemporary or persistent torque reductions or increases.

The axle torque requests 256 may include a torque reduction requested bya traction control system when positive wheel slip is detected. Positivewheel slip occurs when axle torque overcomes friction between the wheelsand the road surface, and the wheels begin to slip against the roadsurface. The axle torque requests 256 may also include a torque increaserequest to counteract negative wheel slip, where a tire of the vehicleslips with respect to the road surface because the axle torque isnegative.

The axle torque requests 256 may also include brake management requestsand vehicle over-speed torque requests. Brake management requests mayreduce axle torque to ensure that the axle torque does not exceed theability of the brakes to hold the vehicle when the vehicle is stopped.Vehicle over-speed torque requests may reduce the axle torque to preventthe vehicle from exceeding a predetermined speed. The axle torquerequests 256 may also be generated by vehicle stability control systems.

The axle torque arbitration module 204 outputs a predicted torquerequest 257 and an immediate torque request 258 based on the results ofarbitrating between the received torque requests 253 and 256. Asdescribed below, the predicted and immediate torque requests 257 and 258from the axle torque arbitration module 204 may selectively be adjustedby other modules of the ECM 114 before being used to control actuatorsof the engine system 100.

In general terms, the immediate torque request 258 is the amount ofcurrently desired axle torque, while the predicted torque request 257 isthe amount of axle torque that may be needed on short notice. The ECM114 controls the engine system 100 to produce an axle torque equal tothe immediate torque request 258. However, different combinations ofactuator values may result in the same axle torque. The ECM 114 maytherefore adjust the actuator values to allow a faster transition to thepredicted torque request 257, while still maintaining the axle torque atthe immediate torque request 258.

In various implementations, the predicted torque request 257 may bebased on the secured engine torque request 253. The immediate torquerequest 258 may be less than the predicted torque request 257, such aswhen the secured engine torque request 253 is causing wheel slip on anicy surface. In such a case, a traction control system (not shown) mayrequest a reduction via the immediate torque request 258, and the ECM114 reduces the torque produced by the engine system 100 to theimmediate torque request 258. However, the ECM 114 controls the enginesystem 100 so that the engine system 100 can quickly resume producingthe predicted torque request 257 once the wheel slip stops.

In general terms, the difference between the immediate torque request258 and the (generally higher) predicted torque request 257 can bereferred to as a torque reserve. The torque reserve may represent theamount of additional torque (above the immediate torque request 258)that the engine system 100 can begin to produce with minimal delay. Fastengine actuators are used to increase or decrease current axle torque.As described in more detail below, fast engine actuators are defined incontrast with slow engine actuators.

In various implementations, fast engine actuators are capable of varyingaxle torque within a range, where the range is established by the slowengine actuators. In such implementations, the upper limit of the rangeis the predicted torque request 257, while the lower limit of the rangeis limited by the torque capacity of the fast actuators. For exampleonly, fast actuators may only be able to reduce axle torque by a firstamount, where the first amount is a measure of the torque capacity ofthe fast actuators. The first amount may vary based on engine operatingconditions set by the slow engine actuators. When the immediate torquerequest 258 is within the range, fast engine actuators can be set tocause the axle torque to be equal to the immediate torque request 258.When the ECM 114 requests the predicted torque request 257 to be output,the fast engine actuators can be controlled to vary the axle torque tothe top of the range, which is the predicted torque request 257.

In general terms, fast engine actuators can more quickly change the axletorque when compared to slow engine actuators. Slow actuators mayrespond more slowly to changes in their respective actuator values thanfast actuators do. For example, a slow actuator may include mechanicalcomponents that require time to move from one position to another inresponse to a change in actuator value. A slow actuator may also becharacterized by the amount of time it takes for the axle torque tobegin to change once the slow actuator begins to implement the changedactuator value. Generally, this amount of time will be longer for slowactuators than for fast actuators. In addition, even after beginning tochange, the axle torque may take longer to fully respond to a change ina slow actuator.

For example only, the ECM 114 may set actuator values for slow actuatorsto values that would enable the engine system 100 to produce thepredicted torque request 257 if the fast actuators were set toappropriate values. Meanwhile, the ECM 114 may set actuator values forfast actuators to values that, given the slow actuator values, cause theengine system 100 to produce the immediate torque request 258 instead ofthe predicted torque request 257.

The fast actuator values therefore cause the engine system 100 toproduce the immediate torque request 258. When the ECM 114 decides totransition the axle torque from the immediate torque request 258 to thepredicted torque request 257, the ECM 114 changes the actuator valuesfor one or more fast actuators to values that correspond to thepredicted torque request 257. Because the slow actuator values havealready been set based on the predicted torque request 257, the enginesystem 100 is able to produce the predicted torque request 257 afteronly the delay imposed by the fast actuators. In other words, the longerdelay that would otherwise result from changing axle torque using slowactuators is avoided.

For example only, when the predicted torque request 257 is equal to thesecured engine torque request 253, a torque reserve may be created whenthe immediate torque request 258 is less than the secured engine torquerequest 253 due to a temporary torque reduction request. Alternatively,a torque reserve may be created by increasing the predicted torquerequest 257 above the secured engine torque request 253 whilemaintaining the immediate torque request 258 at the secured enginetorque request 253. The resulting torque reserve can absorb suddenincreases in required axle torque. For example only, sudden loadsimposed by an air conditioner or a power steering pump may becounteracted by increasing the immediate torque request 258. If theincrease in the immediate torque request 258 is less than the torquereserve, the increase can be quickly produced by using fast actuators.The predicted torque request 257 may also be increased to re-establishthe previous torque reserve.

Another example use of a torque reserve is to reduce fluctuations inslow actuator values. Because of their relatively slow speed, varyingslow actuator values may produce control instability. In addition, slowactuators may include mechanical parts, which may draw more power and/orwear more quickly when moved frequently. Creating a sufficient torquereserve allows changes in desired torque to be made by varying fastactuators via the immediate torque request 258 while maintaining thevalues of the slow actuators. For example, to maintain a given idlespeed, the immediate torque request 258 may vary within a range. If thepredicted torque request 257 is set to a level above this range,variations in the immediate torque request 258 that maintain the idlespeed can be made using fast actuators without the need to adjust slowactuators.

For example only, in a spark-ignition engine, spark timing may be a fastactuator value, while throttle opening area may be a slow actuatorvalue. Spark-ignition engines may combust fuels including, for example,gasoline and ethanol, by applying a spark. By contrast, in acompression-ignition engine, fuel flow may be a fast actuator value,while throttle opening area may be used as an actuator value for enginecharacteristics other than torque. Compression-ignition engines maycombust fuels including, for example, diesel, by compressing the fuels.

When the engine 102 is a spark-ignition engine, the spark actuatormodule 126 may be a fast actuator and the throttle actuator module 116may be a slow actuator. After receiving a new actuator value, the sparkactuator module 126 may be able to change spark timing for the followingfiring event. When the spark timing (also called spark advance) for afiring event is set to a calibrated value, a maximum amount of torquemay be produced in the combustion stroke immediately following thefiring event. However, a spark advance deviating from the calibratedvalue may reduce the amount of torque produced in the combustion stroke.Therefore, the spark actuator module 126 may be able to vary engineoutput torque as soon as the next firing event occurs by varying sparkadvance. For example only, a table of spark advances corresponding todifferent engine operating conditions may be determined during acalibration phase of vehicle design, and the calibrated value isselected from the table based on current engine operating conditions.

By contrast, changes in throttle opening area take longer to affectengine output torque. The throttle actuator module 116 changes thethrottle opening area by adjusting the angle of the blade of thethrottle valve 112. Therefore, once a new actuator value is received,there is a mechanical delay as the throttle valve 112 moves from itsprevious position to a new position based on the new actuator value. Inaddition, air flow changes based on the throttle opening area aresubject to air transport delays in the intake manifold 110. Further,increased air flow in the intake manifold 110 is not realized as anincrease in engine output torque until the cylinder 118 receivesadditional air in the next intake stroke, compresses the additional air,and commences the combustion stroke.

Using these actuators as an example, a torque reserve can be created bysetting the throttle opening area to a value that would allow the engine102 to produce the predicted torque request 257. Meanwhile, the sparktiming can be set based on the immediate torque request 258, which isless than the predicted torque request 257. Although the throttleopening area generates enough air flow for the engine 102 to produce thepredicted torque request 257, the spark timing is retarded (whichreduces torque) based on the immediate torque request 258. The engineoutput torque will therefore be equal to the immediate torque request258.

When additional torque is needed, the spark timing can be set based onthe predicted torque request 257 or a torque between the predicted andimmediate torque requests 257 and 258. By the following firing event,the spark actuator module 126 may return the spark advance to acalibrated value, which allows the engine 102 to produce the full engineoutput torque achievable with the air flow already present. The engineoutput torque may therefore be quickly increased to the predicted torquerequest 257 without experiencing delays from changing the throttleopening area.

When the engine 102 is a compression-ignition engine, the fuel actuatormodule 124 may be a fast actuator and the throttle actuator module 116and the boost actuator module 165 may be emissions actuators. The fuelmass may be set based on the immediate torque request 258, and thethrottle opening area, boost, and EGR opening may be set based on thepredicted torque request 257. The throttle opening area may generatemore air flow than necessary to satisfy the predicted torque request257. In turn, the air flow generated may be more than required forcomplete combustion of the injected fuel such that the air/fuel ratio isusually lean and changes in air flow do not affect the engine outputtorque. The engine output torque will therefore be equal to theimmediate torque request 258 and may be increased or decreased byadjusting the fuel flow.

The throttle actuator module 116, the boost actuator module 165, and theEGR valve 164 may be controlled based on the predicted torque request257 to control emissions and to minimize turbo lag. The throttleactuator module 116 may create a vacuum within the intake manifold 110to draw exhaust gases through the EGR valve 164 and into the intakemanifold 110.

The axle torque arbitration module 204 may output the predicted torquerequest 257 and the immediate torque request 258 to a propulsion torquearbitration module 206. In various implementations, the axle torquearbitration module 204 may output the predicted and immediate torquerequests 257 and 258 to the hybrid optimization module 208.

The hybrid optimization module 208 may determine how much torque shouldbe produced by the engine 102 and how much torque should be produced bythe electric motor 198. The hybrid optimization module 208 then outputsmodified predicted and immediate torque requests 259 and 260,respectively, to the propulsion torque arbitration module 206. Invarious implementations, the hybrid optimization module 208 may beimplemented in the hybrid control module 196.

The predicted and immediate torque requests received by the propulsiontorque arbitration module 206 are converted from an axle torque domain(torque at the wheels) into a propulsion torque domain (torque at thecrankshaft). This conversion may occur before, after, as part of, or inplace of the hybrid optimization module 208.

The propulsion torque arbitration module 206 arbitrates betweenpropulsion torque requests 279, including the converted predicted andimmediate torque requests. The propulsion torque arbitration module 206generates an arbitrated predicted torque request 261 and an arbitratedimmediate torque request 262. The arbitrated torque requests 261 and 262may be generated by selecting a winning request from among receivedtorque requests. Alternatively or additionally, the arbitrated torquerequests 261 and 262 may be generated by modifying one of the receivedrequests based on another one or more of the received torque requests.

The propulsion torque requests 279 may include torque reductions forengine over-speed protection, torque increases for stall prevention, andtorque reductions requested by the transmission control module 194 toaccommodate gear shifts. The propulsion torque requests 279 may alsoresult from clutch fuel cutoff, which reduces the engine output torquewhen the driver depresses the clutch pedal in a manual transmissionvehicle to prevent a flare (rapid rise) in engine speed.

The propulsion torque requests 279 may also include an engine shutoffrequest, which may be initiated when a critical fault is detected. Forexample only, critical faults may include detection of vehicle theft, astuck starter motor, electronic throttle control problems, andunexpected torque increases. In various implementations, when an engineshutoff request is present, arbitration selects the engine shutoffrequest as the winning request. When the engine shutoff request ispresent, the propulsion torque arbitration module 206 may output zero asthe arbitrated predicted and immediate torque requests 261 and 262.

In various implementations, an engine shutoff request may simply shutdown the engine 102 separately from the arbitration process. Thepropulsion torque arbitration module 206 may still receive the engineshutoff request so that, for example, appropriate data can be fed backto other torque requestors. For example, all other torque requestors maybe informed that they have lost arbitration.

The reserves/loads module 220 receives the arbitrated predicted andimmediate torque requests 261 and 262. The reserves/loads module 220 mayadjust the arbitrated predicted and immediate torque requests 261 and262 to create a torque reserve and/or to compensate for one or moreloads. The reserves/loads module 220 then outputs adjusted predicted andimmediate torque requests 263 and 264 to the actuation module 224.

For example only, a catalyst light-off process or a cold start emissionsreduction process may require retarded spark advance. The reserves/loadsmodule 220 may therefore increase the adjusted predicted torque request263 above the adjusted immediate torque request 264 to create retardedspark for the cold start emissions reduction process. In anotherexample, the air/fuel ratio of the engine and/or the mass air flow maybe directly varied, such as by diagnostic intrusive equivalence ratiotesting and/or new engine purging. Before beginning these processes, atorque reserve may be created or increased to quickly offset decreasesin engine output torque that result from leaning the air/fuel mixtureduring these processes.

The reserves/loads module 220 may also create or increase a torquereserve in anticipation of a future load, such as power steering pumpoperation or engagement of an air conditioning (A/C) compressor clutch.The reserve for engagement of the A/C compressor clutch may be createdwhen the driver first requests air conditioning. The reserves/loadsmodule 220 may increase the adjusted predicted torque request 263 whileleaving the adjusted immediate torque request 264 unchanged to producethe torque reserve. Then, when the NC compressor clutch engages, thereserves/loads module 220 may increase the adjusted immediate torquerequest 264 by the estimated load of the NC compressor clutch.

The actuation module 224 receives the adjusted predicted and immediatetorque requests 263 and 264. The actuation module 224 determines how theadjusted predicted and immediate torque requests 263 and 264 will beachieved. The actuation module 224 may be engine type specific. Forexample, the actuation module 224 may be implemented differently or usedifferent control schemes for spark-ignition engines versuscompression-ignition engines.

In various implementations, the actuation module 224 may define aboundary between modules that are common across all engine types andmodules that are engine type specific. For example, engine types mayinclude spark-ignition and compression-ignition. Modules prior to theactuation module 224, such as the propulsion torque arbitration module206, may be common across engine types, while the actuation module 224and subsequent modules may be engine type specific.

For example, in a spark-ignition engine, the actuation module 224 mayvary the opening of the throttle valve 112 as a slow actuator thatallows for a wide range of torque control. The actuation module 224 maydisable cylinders using the cylinder actuator module 120, which alsoprovides for a wide range of torque control, but may also be slow andmay involve drivability and emissions concerns. The actuation module 224may use spark timing as a fast actuator. However, spark timing may notprovide as much range of torque control. In addition, the amount oftorque control possible with changes in spark timing (referred to asspark reserve capacity) may vary as air flow changes.

In various implementations, the actuation module 224 may generate an airtorque request 265 based on the adjusted predicted torque request 263.The air torque request 265 may be equal to the adjusted predicted torquerequest 263, setting air flow so that the adjusted predicted torquerequest 263 can be achieved by changes to other actuators.

The air control module 228 may determine desired actuator values basedon the air torque request 265. For example only, the air control module228 may determine a desired manifold absolute pressure (MAP) 266, adesired throttle position 267, and/or a desired air per cylinder (APC)268 based on the air torque request 265. The desired MAP 266 may be usedto determine a desired boost, and the desired APC 268 may be used todetermine desired cam phaser positions and the desired throttle position267. In various implementations, the air control module 228 may alsodetermine an amount of opening of the EGR valve 164 based on the airtorque request 265.

The actuation module 224 may also generate a spark torque request 269, acylinder shut-off torque request 270, and a fuel torque request 271. Thespark torque request 269 may be used by the spark control module 232 todetermine how much to retard the spark timing (which reduces engineoutput torque) from a calibrated spark timing.

The cylinder shut-off torque request 270 may be used by the cylindercontrol module 236 to determine how many cylinders to deactivate. Thecylinder control module 236 may instruct the cylinder actuator module120 to deactivate one or more cylinders of the engine 102. In variousimplementations, a predefined group of cylinders (e.g., half) may bedeactivated jointly.

The cylinder control module 236 may also instruct the fuel controlmodule 240 to stop providing fuel for deactivated cylinders and mayinstruct the spark control module 232 to stop providing spark fordeactivated cylinders. In various implementations, the spark controlmodule 232 only stops providing spark for a cylinder once any fuel/airmixture already present in the cylinder has been combusted.

In various implementations, the cylinder actuator module 120 may includea hydraulic system that selectively decouples intake and/or exhaustvalves from the corresponding camshafts for one or more cylinders inorder to deactivate those cylinders. For example only, valves for halfof the cylinders are either hydraulically coupled or decoupled as agroup by the cylinder actuator module 120. In various implementations,cylinders may be deactivated simply by halting provision of fuel tothose cylinders, without stopping the opening and closing of the intakeand exhaust valves. In such implementations, the cylinder actuatormodule 120 may be omitted.

The fuel control module 240 may vary the amount of fuel provided to eachcylinder based on the fuel torque request 271. During normal operationof a spark-ignition engine, the fuel control module 240 may operate inan air lead mode in which the fuel control module 240 attempts tomaintain a stoichiometric air/fuel ratio by controlling fueling based onair flow. The fuel control module 240 may determine a fuel mass thatwill yield stoichiometric combustion when combined with the currentamount of air per cylinder. The fuel control module 240 may instruct thefuel actuator module 124 via a fueling rate to inject this fuel mass foreach activated cylinder.

In compression-ignition systems, the fuel control module 240 may operatein a fuel lead mode in which the fuel control module 240 determines afuel mass for each cylinder that satisfies the fuel torque request 271while minimizing emissions, noise, and fuel consumption. In the fuellead mode, air flow is controlled based on fuel flow and may becontrolled to yield a lean air/fuel ratio. In addition, the air/fuelratio may be maintained above a predetermined level, which may preventblack smoke production in dynamic engine operating conditions.

The air control module 228 may output the desired throttle position 267to a throttle control module 280. The air control module 228 maydetermine the desired throttle position 267 based on the air torquerequest 265. The throttle control module 280 generates a desired pulsewidth modulation (PWM) signal 282 using closed-loop control based on thedesired throttle position 267. The throttle actuator module 116 actuatesthe throttle valve 112 based on the desired PWM signal 282. Morespecifically, the desired PWM signal 282 may drive (e.g., a motor of)the throttle actuator module 116 to actuate the throttle valve 112.While the desired PWM signal 282 is shown and discussed, the throttlecontrol module 280 may control the throttle actuator module 116 usinganother suitable type of signal.

The air control module 228 may output the desired MAP 266 to the boostscheduling module 248. The boost scheduling module 248 uses the desiredMAP 266 to control the boost actuator module 165. The boost actuatormodule 165 then controls one or more turbochargers (e.g., theturbocharger including the turbine 160-1 and the compressor 160-2)and/or superchargers.

The air control module 228 outputs the desired APC 268 to the phaserscheduling module 252. Based on the desired APC 268 and the RPM signal,the phaser scheduling module 252 may control positions of the intakeand/or exhaust cam phasers 148 and 150 using the phaser actuator module158.

Referring back to the spark control module 232, the calibrated sparktiming may vary based on various engine operating conditions. Forexample only, a torque relationship may be inverted to solve for desiredspark advance. For a given torque request (T_(des)), the desired sparkadvance (S_(des)) may be determined based on

S _(des) =T ⁻¹(T _(des),APC,I,E,AF,OT,#).   (1)

This relationship may be embodied as an equation and/or as a lookuptable. The air/fuel ratio (AF) may be the actual air/fuel ratio, asreported by the fuel control module 240.

When the spark advance is set to the calibrated spark timing, theresulting torque may be as close to a maximum best torque (MBT) aspossible. MBT refers to the maximum engine output torque that isgenerated for a given air flow as spark advance is increased, whileusing fuel having an octane rating greater than a predetermined octanerating and using stoichiometric fueling. The spark advance at which thismaximum torque occurs is referred to as an MBT spark timing. Thecalibrated spark timing may differ slightly from MBT spark timingbecause of, for example, fuel quality (such as when lower octane fuel isused) and environmental factors. The engine output torque at thecalibrated spark timing may therefore be less than MBT.

Referring now to FIG. 3, an example of the driver torque module 202 isshown. The driver torque module 202 may include a driver interpretationmodule 304, an engine torque request module 308, a DRPM determinationmodule 312, a secured torque determination module 316, a torque boundarydetermination module 320, an engine torque response module 324, and atorque command limit module 328.

The driver interpretation module 304 generates an engine power request(P_(E)) based on the driver input 254 and the vehicle speed 255. Asstated above, the driver input 254 may include an accelerator pedalposition and/or one or more other suitable parameters, such as a brakepedal position and cruise control inputs. The vehicle speed 255 may begenerated based on, for example, one or more wheel speeds, thetransmission output shaft speed, and/or one or more other parameters.The driver interpretation module 304 may generate the engine powerrequest P_(E) using a function and/or a mapping that relates theaccelerator pedal position and the vehicle speed 255 to the engine powerrequest P_(E). The function and/or mapping may be calibrated such thatthe vehicle achieves a desired acceleration for the vehicle speed 255and the accelerator pedal position.

The engine torque request module 308 generates an engine torque request(T_(E)) based on the engine power request P_(E). The engine torquerequest module 308 generates the engine torque request T_(E) furtherbased on the DRPM. The DRPM may be determined for purposes of thedetermining the engine torque request T_(E). The DRPM determinationmodule 312 determines the DRPM. The DRPM determination module 312determines the DRPM based on the engine power request P_(E), turbinespeed (TS), and slip. For example, the slip may be torque converterclutch (TCC) slip. The DRPM determination module 312 may also generatethe DRPM based on other operating parameters such as those described incommonly-assigned U.S. patent application Ser. No. 13/166,232, filed onJun. 22, 2011, which was herein incorporated by reference in itsentirety.

The engine torque request module 312 generates the engine torque requestT_(E) by converting the engine power request P_(E) into a torque usingthe DRPM. More specifically, the engine torque request module 312 maygenerate the engine torque request T_(E) as follows:

$\begin{matrix}{T_{E} = {\frac{P_{E}}{DRPM}.}} & (2)\end{matrix}$

The engine torque request module 38, however, generates the enginetorque request T_(E) using feed-forward (FF) control to decrease theperiod between when a change in the engine torque request T_(E) is madeand when the engine 102 outputs torque corresponding to the enginetorque request T_(E). For example only, the feed-forward control mayinclude a first-order correction. Additionally, for example only, theengine torque request module 308 may determine the engine torque requestT_(E) as follows:

$\begin{matrix}{{ETR}_{k} = {\frac{{FFP}_{k}}{{DRPM}_{k}}.}} & (3)\end{matrix}$

where ETR_(k) is the engine torque request T_(E) at a given time k,DRPM_(k) is the DRPM at the given time k, and FFP_(k) is a feed-forwardpower determined for the given time k as follows:

FFP_(k) =a(ETR_(k)−ETR_(k−1))+FFP_(k−1) +b(ETR_(k−1)),   (4)

where ETR_(k) is the engine power request P_(E) at the given time k,EPR_(k−1) is the engine power request P_(E) at a previous time k−1,FFP_(k−1) is value of FFP at the previous time k−1, and a and b arepredetermined values calibrated to cause the engine 102 to achieve theengine power request P_(E) and the engine torque request T_(E) earlierthan if equation (3) above was used to generate the engine torquerequest T_(E). The time k may be the time for a present control loop,and the previous time k−1 may be the time for a previous control loop.

The secured torque determination module 316 determines a secured torque(T_(S)). The secured torque determination module 316 may determine thesecured torque T_(S) based on the engine power request P_(E). Thesecured torque determination module 316 may determine the secured torqueT_(S) further based on engine speed (RPM). The engine speed RPM may bemeasured by the engine speed sensor 170. More specifically, the securedtorque determination module 316 may determine the secured torque T_(S)as follows:

$\begin{matrix}{T_{S} = {\frac{P_{E}}{RPM}.}} & (5)\end{matrix}$

The torque boundary determination module 320 determines torqueboundaries (T_(MAM), T_(MIN)). The torque boundary determination module320 may determine the torque boundaries T_(MAX), T_(MIN) based on thesecured torque T_(S). The torque boundary determination module 320 maydetermine the torque boundaries T_(MAX), T_(MIN) further based on driverinput 254 and vehicle speed 255. More specifically, the torque boundarydetermination module 320 may determine the torque boundaries T_(MAX),T_(MIN) by determining a variation from the secured torque T_(S). Forexample, the variation may be determined as a function of the driverinput 254 and the vehicle speed 255.

The engine torque response module 324 determines maximum and minimumtorque values (Max, Min). The maximum and minimum torque values Max, Minrepresent maximum and minimum acceptable torque values for preventingdisturbances in vehicle drivability. The engine torque response module324 may determine the maximum and minimum torque values Max, Min usingan engine torque response model. For example, the engine torque responsemodel may be applied individually to the torque boundaries T_(MAX) andT_(MIN) to generate the maximum and minimum torque values Max and Min,respectively. The engine torque response model may further apply timedelay(s) and/or rate limits to the maximum torque value Max and/or theminimum torque value Min.

The torque command limit module 328 generates the secured engine torquerequest 253. The torque command limit module 328 may generate thesecured engine torque request 253 based on the engine torque requestT_(E). The torque command limit module 328 may generate the securedengine torque request 253 further based on the maximum and minimumtorque values Max, Min. The torque command limit module 328 may limitthe engine torque request T_(E) to the maximum and minimum torque valuesMax, Min. More specifically, the torque command limit module maygenerate the secured engine torque request 253 as follows:

Min≦T_(ES)≦Max,   (6)

where T_(ES) represents the secured engine torque request 253 limited(or constrained) by the maximum and minimum torque values Max, Min.

Referring now to FIG. 4, an example method for improved vehicledrivability for engine torque control based on desired engine speedbegins at 400. At 400, the ECM 114 determines an engine power requestP_(E) based on driver input 254 and vehicle speed 255. At 404, the ECM114 determines DRPM based on the engine power request P_(E), turbinespeed TS, and TCC slip. At 408, the ECM 114 determines an engine torquerequest T_(E) based on the engine power request P_(E) and the DRPM. At412, the ECM 114 determines a secured torque T_(S) based on the enginepower request and engine speed RPM.

At 416, the ECM 114 determines torque boundaries T_(MAX), T_(MIN) basedon the secured torque T_(S), driver input 254, and vehicle speed 255. At420, the ECM 114 determines maximum and minimum torque values Max, Minbased on the torque boundaries T_(MAX), T_(MIN) and an engine torqueresponse model. At 424, the ECM 114 generates a secured engine torquerequest based on the engine torque request T_(E) and the maximum andminimum torque values Max, Min. At 428, the ECM 114 controls the engine102 based on the secured engine torque request. Control may then end orloop back to 400 for another cycle.

The broad teachings of the disclosure can be implemented in a variety offorms. Therefore, while this disclosure includes particular examples,the true scope of the disclosure should not be so limited since othermodifications will become apparent to the skilled practitioner upon astudy of the drawings, the specification, and the following claims.

What is claimed is:
 1. A control system for an engine, the controlsystem comprising: an engine torque request module that determines anengine torque request based on (i) an engine power request and (ii) adesired engine speed (DRPM); an engine torque response module thatdetermines first and second torque values based on (i) an engine torqueresponse model and (ii) first and second torque boundaries, wherein thefirst and second torque boundaries are based on the DRPM and a measuredengine speed (RPM); a torque command limit module that generates asecured engine torque request based on (i) the engine torque request and(ii) the first and second torque values; and an actuation module thatcontrols at least one actuator of the engine based on the secured enginetorque request.
 2. The control system of claim 1, further comprising adriver interpretation module that determines the engine power requestbased on (i) driver input and (ii) vehicle speed.
 3. The control systemof claim 2, further comprising a DRPM determination module thatdetermines the DRPM based on (i) the engine power request, (ii) turbinespeed, and (iii) torque converter clutch slip.
 4. The control system ofclaim 3, wherein the engine torque request module includes afeed-forward controller that determines the engine torque request basedon (i) the engine power request and (ii) the DRPM.
 5. The control systemof claim 3, further comprising a secured torque determination modulethat determines the secured torque based on (i) the DRPM and (ii) theRPM.
 6. The control system of claim 5, further comprising a torqueboundary determination module that determines the first and secondtorque boundaries based on (i) the secured torque, (ii) the driverinput, and (iii) vehicle speed.
 7. The control system of claim 6,wherein the driver input includes at least one of (i) accelerator pedalposition, (ii) brake pedal position, and (iii) a cruise control input.8. The control system of claim 1, wherein the engine torque responsemodel includes at least one of (i) a time delay and (ii) a rate limit.9. The control system of claim 1, wherein the torque command limitmodule generates the secured engine torque request by limiting theengine torque request to a value between the first and second torquevalues.
 10. The control system of claim 1, wherein controlling the atleast one actuator of the engine includes controlling at least one ofair, fuel, and spark provided to the engine.
 11. A method forcontrolling an engine, the method comprising: determining an enginetorque request based on (i) an engine power request and (ii) a desiredengine speed (DRPM); determining first and second torque values based on(i) an engine torque response model and (ii) first and second torqueboundaries, wherein the first and second torque boundaries are based onthe DRPM and a measured engine speed (RPM); generating a secured enginetorque request based on (i) the engine torque request and (ii) the firstand second torque values; and controlling at least one actuator of theengine based on the secured engine torque request.
 12. The method ofclaim 11, further comprising determining the engine power request basedon (i) driver input and (ii) vehicle speed.
 13. The method of claim 12,further comprising determining the DRPM based on (i) the engine powerrequest, (ii) turbine speed, and (iii) torque converter clutch slip. 14.The method of claim 13, determining the engine torque request based on(i) the engine power request and (ii) the DRPM, using a feed-forwardcontroller.
 15. The method of claim 13, further comprising determiningthe secured torque based on (i) the DRPM and (ii) the RPM.
 16. Themethod of claim 15, further comprising determining the first and secondtorque boundaries based on (i) the secured torque, (ii) the driverinput, and (iii) vehicle speed.
 17. The method of claim 16, wherein thedriver input includes at least one of (i) accelerator pedal position,(ii) brake pedal position, and (iii) a cruise control input.
 18. Themethod of claim 11, wherein the engine torque response model includes atleast one of (i) a time delay and (ii) a rate limit.
 19. The method ofclaim 11, further comprising generating the secured engine torquerequest by limiting the engine torque request to a value between thefirst and second torque values.
 20. The method of claim 11, whereincontrolling the at least one actuator of the engine includes controllingat least one of air, fuel, and spark provided to the engine.